The present invention relates to Class D12, Transportation, Subclass 6, Sled. The present invention relates to various systems used for steering and speed control of snow vehicles.
The control of the direction of movement of a snow vehicle is usually obtained by either changing the position of the front ski of a vehicle using a total of two or three skis (one front ski used for steering/support and one or two rear skis used only for support on the snow) or by changing the direction of the two front skis of a vehicle using three or four skis (two front skis used for steering/support and one or two rear skis used only for support on the snow). In the case of a powered snow vehicle like a snowmobile, the rear support is replaced by a powered endless track.
Vehicles using a single front ski for steering must use different means for braking or must rely on the ability of the operator to stop by turning the vehicle perpendicular to the initial direction of motion. The U.S. Pat. No. 8,523,195 describes a snow vehicle that employs braking members that are lowered to contact the snow, so as to create friction or resistance with respect to the snow on the ground. The disadvantage of the method is that the steering ability is substantially reduced during braking due to the increased friction from the braking members. By contrast, the U.S. Pat. No. 5,863,051 describes a snow vehicle that has no braking provisions.
Vehicles using two front skis for steering usually turn both skis in the same direction for steering and they are facing the same problem as the single front ski vehicles when they need to brake. The U.S. Pat. No. 8,590,654 B2 describes a snowmobile that uses the endless track for braking by decupling it from the motor and locking it. To avoid skidding, an antilock braking system (ABS) can be used.
Vehicles using two front skis for steering could use the wedge technique (plow skiing) for speed control and steering, as described in U.S. Pat. No. 3,682,495. In this embodiment, the operator's ability to control the front skis will determine the precision of the steering and the efficiency of the braking.